Modular rotary tools of the aforementioned type, such as drills or drilling tools, extend in the longitudinal or axial direction along an axis of rotation and have two coupling parts, namely a carrier and a cutting head, wherein the cutting head is exchangeably secured on the carrier. For this purpose, the carrier usually has on its end surface two opposite securing webs, which are separated from each other by flutes and by which a pin receiving means or coupling receiving means is delimited. In the secured state, a coupling pin of the cutting head is inserted into this coupling receiving means. This is carried out, for example, by turning the cutting head about the axis of rotation relative to the carrier. During this bayonet-like turning, a clamping connection between the cutting head and the carrier is created so that the two coupling parts are held together in a clamping manner. In particular, no additional securing means, such as screws or the like, are provided therein.
From U.S. Pat. No. 7,360,974 B2 is known a rotary tool with a carrier and with a cutting head exchangeably secured on said carrier. The coupling connection in the secured state is in this case carried out by means of outer webs formed on the coupling pin. The webs have a helical course and are designed in the manner of a screw thread. When screwing in or turning the cutting head, the cutting head is axially tightened as a result.
US 2017/0028480 A1 discloses a rotary tool, which has an essentially cuboidal coupling pin (with the exception of any recesses due to grooves), which is designed with a web arranged on the end surface of the coupling pin and extending circumferentially, in order to prevent pulling-out in an axial direction. The web transitions into clamping and torque surfaces while forming a step. The step in this case forms a horizontal contact surface that acts as protection against pulling-out in an axial direction. The clamping surfaces are in this case formed by a radial cut-in.
In order to improve the service life of such rotary tools, it is, for example, possible to integrate into the carrier, cooling structures, such as coolant lines or coolant channels, which open into respective cooling structures of the cutting head or into a flute, for example, and guide a coolant and/or lubricant during operation.
In rotary tools with cutting heads with integrated cooling structures, the coolant channels of the carrier typically emerge at a bottom surface of the coupling receiving means and are aligned there with corresponding coolant channels of the cutting head, which guide the coolant/lubricant along a cutting-head end surface or tool tip. In particular in applications or operating situations in which the end surface of the cutting head is free, i.e. does not have any material contact on the front side with a workpiece as, for example, in predrilled holes or cut-outs, the problem often occurs that the coolant/lubricant escapes at the cutting-head end surface and that the cutting head or the carrier is not wetted or cooled/lubricated. This disadvantageously reduces the service life of the rotary tool.